Electro-mechanical actuators are commonly used in automobiles for the purpose of manipulating locking door latches. Actuators in this application are typically user-operated by rotation of a key in the door key cylinder. Key rotation causes the motor-driven actuator to physically vary the door lock state by manipulation of various door lock levers.
For example, in a typical double-locking door latch, the door handle inside the vehicle and the door handle outside of the vehicle may be locked/unlocked independently of each other. This is accomplished by means of actuator manipulation of adjacent lock pawls which act against respective latch levers. In an "unlock" mode, the pawls push directly against the latch levers, and in a "lock" mode, the pawls are lifted up (e.g., rotated about a pin) to slide past the engagement surfaces of the latch levers.
Unfortunately, prior art door lock actuators have proven to be cumbersome, costly, and inefficient in design. One reason for this is that prior art designs require incorporation of either a reversible drive motor capable of driving the actuator in two directions of rotation, a separate drive motor for each direction of rotation, or a separate drive motor for each lock pawl. However, reversible drive motors are relatively expensive compared to non-reversible motors, and the combination of two drive motors results in a physically large actuator assembly which may be difficult to incorporate into limited space. Prior art designs have also failed to provide reliable manual override systems for allowing manipulation of the door lock in the event of total loss of electrical power. In some cases, prior art manual override systems require excessive force to activate, or are ineffective due to inappropriate physical positioning of the lock pawls.
Accordingly, there is a need in the art for a cost-effective, compact, and reliable door lock actuator. There is also a need in the art for door lock actuator with a reliable and effective manual override mechanism.